1. Field of the Present Invention
The present invention relates to a wiring substrate and a semiconductor device having a semiconductor element formed by a droplet discharging method typified by an ink-jet method, and further manufacturing methods thereof.
2. Description of the Related Art
Conventionally, an active matrix driving type display panel or semiconductor integrated circuit including a semiconductor element typified by a thin film transistor (hereinafter, TFT) or a MOS transistor is formed by patterning each thin film with light-exposure process (hereinafter, a photolithography process) using a photomask.
In the photolithography process, resist is applied to a whole substrate, pre-baked, then the substrate is irradiated with ultraviolet rays or the like using a photomask and a resist pattern is formed by development. After that, a thin film existing outside a portion to be a film pattern or a wiring (a film of a semiconductor material, an insulator material, or a conductor material) is etch-removed with the resist pattern as a mask pattern for forming a film-pattern or a wiring.
Reference 1 (Japanese Patent Laid-Open No. 2000-188251) describes a technique for forming a film on a semiconductor wafer with an apparatus that can continuously discharge resist from its nozzle to have a linear shape with a small diameter so as to reduce loss of materials for forming films.
However, when forming a wiring or a film-pattern using a conventional photolithography process, almost all materials of the wiring or the film pattern and a resist material become wasted and the number of steps of forming the wiring or a mask pattern becomes large; therefore throughput is decreased.
A light-exposure apparatus used in the photolithography process has difficulty in exposing a large substrate to light at once. Accordingly, a manufacturing method of a semiconductor device using a large substrate needs a plurality of times of light-exposure, which leads to misalignment with an adjacent pattern and reduction in yield.
It is necessary to discharge a material solution whose droplet diameter is small in order to form a semiconductor element that is minute and occupies a small area by a droplet-discharging method. Reduction in diameter of the discharge opening is required to be small so as to discharge such a material solution. However, in this case, the tip of the discharge opening is clogged with the material solution because a composition of the material solution is attached thereto, dried or solidified therein, and thus it is difficult to discharge a constant amount of material solution continuously or stably. Consequently, there is a problem in that throughput or yield of a semiconductor device using the semiconductor element is reduced.